Step 1: Download and copy the latest IOS (XE) to the 3850 flash via USB or TFTP.
Step 2: Check the mode (Install or Bundle) of the switch by entering following command:
Switch#show version | begin Switch Ports
The out put will be as below:
Note: If the Switch is not in INSTALL Mode it’s highly recommended to switch INSTALL mode from BUNDLE mode. Click here to find out how or enter the below commands:
# software expand running to flash: (config)#boot system flash:packages.conf
Step 3: Enter the following command to start installing the new IOS using the new code on the flash
Switch#:software install file flash:<New_IOS_File_Name>.bin
Example: Switch#:software install file flash:cat3k_caa-universalk9.SPA.03.03.00.SE.150-1.EZ.bin
Then following will be shown:
Step 4: enter yes and hit enter.
NOTE: Ran into some issue booting 3850. This might be helpful if your Catalyst 3850 Fails to Boot.
3850-access#show boot ————————— Switch 1 ————————— Current Boot Variables: BOOT variable = flash:packages.conf; Boot Variables on next reload: BOOT variable = flash:packages.conf Allow Dev Key = yes Manual Boot = yes Enable Break = no
Notice it’s set to Manual Boot = yes
you need to change that to NO
#conf t (config)#no boot manual #reload
If this also doesn’t fix the boot issue refer the following blog post here.